Cyclone filters, also called centrifugal force separator, cyclone or cyclone separator, are used to separate solid or liquid particles contained in gases. In the cyclone filter, gases together with the particles are set into a rotating movement by a corresponding constructive design. The centrifugal forces acting on the particles accelerate them radially outwards. As a result, they are separated from the gas flow, which is guided inwardly and discharged.
Due to the moderate filtration performance with very fine particles compared with other methods, the cyclone filtration is often used as part of a filter chain in a multi-stage filter system. For separating fine dust particles it is, therefore, state-of-the-art to equip the cyclone filter additionally with a conventional filter element. The air pre-cleaned by the cyclone filtration is conveyed through the filter medium of the final filter, in particular of a filter element, wherein impurities of the air are deposited on the filter medium. By so doing, it is possible to enhance the filtration performance of the cyclone filter.
The state-of-the-art filter elements are often insufficiently adapted to cope with the special requirements for being used as main filter element in an air filtering downstream of the cyclone filtration in an air filter. One problem, in particular, is that the air is swirled after the cyclone filtration. As a result, the filter medium of the final filter is flowed through irregularly, thus reducing the filtering effect.
Furthermore, conventional state-of-the-art filter elements are commonly equipped with filter media having cross-sections in even, round or oval shape. As a result, the available filtering surface of the filter medium is not optimal, for a filtering surface as large as possible is advantageous.